Lots of information here outlining the process from milk, to cream, to butter. I was particularly interested in the barrel churn, an 18th century innovation:
A barrel churn is so late an invention, that the uses of it are known but in few counties in England. Buckinghamshire and Bedfordshire justly claim the first practice of this most serviceable dairy utensil, that every year comes more and more into fashion, for its being easily and quickly clean'd, as well as its being work'd with much facility and least waste of cream, and expeditiously producing the sweetest butter.
William Ellis, The country housewife's family companion , 1750
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